Coating resin composition based on a graft copolymerized resin and method of producing the same

ABSTRACT

A coating resin composition, comprising a graft copolymerized resin prepared by graft polymerizing a monomer containing ethylenic unsaturated bond and a monomer containing an ethylenic unsaturated bond and a hydroxyl group, wherein the hydroxyl group content of the monomer is such that the hydroxyl group content of the graft copolymerized resin is 0.1 to 5 wt. %, onto a mixed resin of (i) a carboxyl group containing chlorinated polyolefin resin containing from 1 to 10 wt. % of α,β-unsaturated carboxylic acid (anhydride) and having a chlorine content of 5 to 50 wt. %, the resin (i) being prepared by a graft polymerizing α,β-unsaturated carboxylic acid (anhydride) onto a polyolefin followed by chlorination, and (ii) an oxidized chlorinated polyolefin resin containing from 5 to 50 wt. % chlorine and having a functional group index of at least 1, prepared by oxidizing and chlorinating a polyolefin, wherein the oxidizing agent for the oxidation is at least one member selected from the group consisting of air, oxygen and ozone, the weight percent ratio of resin (i) to resin (ii) ranging from 5:95 to 95:5 and wherein the mixed resins (i) and (ii) constitute from 5 to 90 wt. % of the components of the composition; and an isocyanate or alkyl-etherified amino resin as a curing agent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a coating composition used for thepurpose of protection and beautifying various plastics and to a methodof producing the same. In more detail, it relates to a resin compositionfor paint and adhesive, which shows excellent physical properties forfilm, sheet or moldings of various synthetic resins such as polyolefinresins, polyurethane resins, polyamide resins, acrylic resins andpolyester resins.

2. Description of the Background

Plastics have many advantages such as high producibility, wide freedomof design, light weight, rust resistance and shock resistance, hencethey are used widely as materials for parts of automobiles, electricalparts, building materials, and the like. Above all, since polyolefinicresins are low in cost and have many excellent properties such asmoldability, chemical resistance, heat resistance, water resistance andgood electrical characteristics, the resins are used extensively asindustrial materials and are one of the materials that growth in demandis most expected in future. Different from synthetic resins which havepolarity such as polyurethane resins, polyamide resins, acrylic resinsand polyester resins, however, polyolefinic resins have the drawbacks ofbeing difficult to paint and adhesion because of nonpolarity andcrystallinity.

For this reason, the surfaces of polyolefinic resin moldings have beenactivated by plasma treatment or gas flame treatment in order to improveadherence, but this method has the drawback that the process iscomplicated, and is accompanied by a great deal of equipment cost andtime loss. Moreover, the effect of surface treatment fluctuates due tothe complexity in the shape of moldings and the influence of pigment andadditives in resin, and the like.

In a method of painting without employing such a pretreatment, variousprimer compositions are used as can be seen in the painting ofpolypropylene bumpers of automobiles. However, these methods areencumbered with the troublesomeness of two-coat finishings.

As coating compositions for one-coat finishing, use has been made ofchlorinated polyolefin, cyclized rubber, etc. that have strong adherentforce to polyolefinic resins, but they exhibit poor weather resistance,moisture resistance, gasoline resistance, etc., resulting ininsufficient performance of coated films. For this reason, attempts havebeen made to admix acrylic resin or alkyd resin having good physicalproperties as a paint for use. However, since acrylic resins or alkydresins have poor compatibility inherently with chlorinated polyolefins,problems arise of decreased gloss of coated film, remarkably injuredappearance, etc.

For improving these drawbacks, a coating composition prepared bycopolymerizing acrylic monomer with chlorinated polyolefin is proposedin Japanese Unexamined Patent Publication No. Sho 58-71966. A paintcomposition having chlorinated polyolefin-modified hydroxylgroup-containing acrylic copolymer copolymerized hydroxylgroup-containing acrylic monomer or the like with chlorinated polyolefinand an isocyanate compound as essential components is proposed inJapanese Unexamined Patent Publication No. Sho 59-27968. An adhesiveresin composition having hydroxyl group-containing acrylic-modifiedchlorinated polyolefin copolymerized hydroxyl group-containing acrylicmonomer or the like in the presence of chlorinated polyolefin and liquidrubber and isocyanate compound as major components is proposed inJapanese Unexamined Patent Publication No. Sho 62-95372. Furthercompositions containing copolymer copolymerized chlorinated polyolefinwith long-chain hydroxyl group-containing vinyl monomer, unsaturatedcarboxylic acid, unsaturated polyester resin or the like, isocyanatecompound, ultraviolet absorber and antioxidant are proposed in JapaneseUnexamined Patent Publication Nos. Hei 5-9428 and Hei 5-194910. However,chlorinated polyolefin has very poor reactivity with copolymerizablemonomers or resins aforementioned. Hence, when copolymerizing with theseformulations milky turbidity and two-layer separation may occur,resulting in no uniform and transparent solution that cannot become agood binder resin for paint, primer, adhesive, etc.

The inventors already proposed methods of preparing uniform andtransparent binder resins in Japanese Unexamined Patent Publication Nos.Hei 5-263038 and Hei 6-108004. In one method, after graft copolymerizingchlorinated polyolefin with hydroxyl group-containing monomer, thecopolymer is reacted with organic diisocyanate and high-molecularpolyol. In another method chlorinated polyolefin is provided with anoxidation treatment with air, oxygen, ozone or the like during thechlorination of a polyolefin and urethanated with an organicdiisocyanate and a high-molecular polyol, followed by grafting withacrylic monomer. While these methods are excellent as methods ofobtaining a uniform and transparent binder resin, however, they have thedrawback of poor adherence to polyolefins and upper-coating paints.

The invention has solved the problems as described above by reacting amixture of chlorinated polyolefins modified by different methods withcopolymerizable monomers, and is directed to providing a binder resinfor paint, primer, adhesive, etc. which is improved over conventionalmodified products of chlorinated polyolefins.

SUMMARY OF THE INVENTION

A coating resin composition comprises a graft copolymerized resinprepared by graft copolymerizing a monomer containing an ethylenicunsaturated bond and a monomer containing ethylenic unsaturated bond anda hydroxyl group onto a mixed resin of (i) a carboxyl group-containingchlorinated polyolefin resin obtained by graft copolymerizing anα,β-unsaturated carboxylic acid (anhydride) onto a polyolefin followedby chlorination and (ii) a chlorinated polyolefin resin obtained bysimultaneously oxidizing and chlorinating a polyolefin using at leastone oxidizing agent selected from air, oxygen and ozone, an isocyanatecompound or an alkyl-etherified amino resin as a curing agent.

The carboxyl group-containing chlorinated polyolefin resin of the resincomposition of the invention can be obtained in such a way that apolyolefinic resin, for example, crystalline polypropylene, amorphouspolypropylene, polybutene-1, polypentane-1, 4-methylpentene-1,low-density or high-density polyethylene or ethylene-propylene copolymeris thermally molten solely or in combination of two or more of suchresins, or, if need be, a polyolefin with viscosity reduced by thermaldecomposition is melted and graft copolymerized batchwise orcontinuously with an α,β-unsaturated carboxylic acid and/or itsanhydride in the presence of a radical-generating agent. This materialis then dispersed or dissolved into a medium such as water, carbontetrachloride or chloroform and reacted with chlorine gas blowing-inwithin a temperature range from 50° to 120° C. under a pressure orambient pressure in the presence of a radical-generating catalyst or byirradiation with ultraviolet rays.

The radical-generating agents to be used for the graft copolymerizationreaction include, for example, peroxides such as di-tert-butyl peroxide,tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butylperoxide benzoate, methyl ethyl ketone peroxide and di-tert-butyldiperphthalate, and azonitriles such as azobisisobutyronitrile.Moreover, α,β-unsaturated carboxylic acids and their anhydrides to beused for the graft copolymerization reaction include, for example,acrylic acid, methacrylic acid, maleic acid, maleic anhydride,citraconic acid, citraconic anhydride, fumaric acid, mesaconic acid,itaconic acid, itaconic anhydride, aconitic acid and aconitic anhydride.

The content of α,β-unsaturated carboxylic acid and/or its anhydride inthe carboxyl group-containing chlorinated polyolefin resin is preferably1 to 10 wt. %. If the content is less than 1 wt. %, the graft reactivitywith ethylenic unsaturated bond-containing monomer etc. becomesinsufficient, resulting in milky turbidity or two-layer separation ofthe reaction liquor. If the content exceeds 10 wt. %, then gelationoccurs during the grafting reaction with ethylenic unsaturatedbond-containing monomer etc. or the adherence to a polyolefin becomespoor. Also, the chlorine content in the carboxyl group-containingchlorinated polyolefin resin preferably is 5 to 50 wt. %. If thechlorine content is too low, the state of the solution becomes poor and,if the chlorine content is too high, then the adherence to polyolefinbecomes poor.

The oxidation treatment-provided chlorinated polyolefin resin to be usedin the invention can be obtained by dispersing or dissolving apolyolefin such as crystalline polypropylene, amorphous polypropylene,polybutene-1, polypentene-1, 4-methylpentene-1, low-density orhigh-density polyethylene, ethylene-propylene copolymer,ethylene-propylene-diene copolymer, natural rubber or polyisoprene intoa medium such as water, carbon tetrachloride or chloroform, chlorinatingwithin a temperature range from 50° to 120° C. under pressure or ambientpressure in the presence of a radical-generating catalyst or byirradiation with ultraviolet rays, and providing with oxidationtreatment by blowing-in air, oxygen or ozone concurrently, separately oralternately with gaseous chlorine beginning, from halfway or at the endof chlorination.

The progress of oxidation of the oxidation treatment-providedchlorinated polyolefin resin can be judged through increased absorptionnear 1730 cm⁻¹ measured by an infrared spectrophotometer. Also, theextent of oxidation can be identified through the functional group indexdetermined by the following formula and, for putting the invention intopractice, said functional group index preferably is 1 or larger.##EQU1##

The chlorine content of oxidized chlorinated polyolefin resin preferablyis within a range from 5 to 50 wt. % for use, since, if it is too low ortoo high, no uniform and transparent reaction liquor results after graftcopolymerization reaction with ethylenic unsaturated bond-containingmonomer etc.

The reacting method for the graft copolymerization of a mixture ofcarboxyl group-containing chlorinated polyolefin resin and oxidationtreatment-provided chlorinated polyolefin resin obtained by the methodsas above with the monomer containing ethylenic unsaturated bond in onemolecule and the monomer containing ethylenic unsaturated bond andhydroxyl group in one molecule has a basic process in that the mixedresins of carboxyl group-containing chlorinated polyolefin resin andoxidation treatment-provide chlorinated polyolefin resin are dilutedsuitably with solvent, then this is warmed, and, after addedpolymerization initiator, the reaction is conducted while graduallyadding monomers. But, the monomers may be mixed beforehand and, afteradded polymerization initiator, the content may be warmed to react.

The mixing ratio by weight of carboxyl group-containing chlorinatedpolyolefin resin to oxidation treatment-provided chlorinated polyolefinresin preferably is 5:95 to 95:5 for graft polymerization. If thecarboxyl group-containing chlorinated polyolefin resin is too little,then the adherence to upper coated paint is poor when used as a primer,and, if the carboxyl group-containing chlorinated polyolefin resin istoo much, then increased viscosity or gelation sometimes occurs duringthe graft copolymerization reaction, which is not desired. On the otherhand, if the amount of oxidation treatment-provided chlorinatedpolyolefin resin is too small, then the reaction liquor becomes opaqueor separates into two layers, resulting in a coated film, which is notglossy, and, if the amount of oxidation treatment-provided chlorinatedpolyolefin resin is too great, then the adherence to upper coated paintis poor, which is not desired.

The solvents to be used for reaction preferably are aromatic solventssuch as toluene and xylene, and, besides, ester solvents such as ethylacetate and butyl acetate, ketone solvents such as methyl ethyl ketoneand methyl isobutyl ketone, alcohol solvents such as ethanol,isopropanol and n-butanol, aliphatic solvents, alicyclic solvents, etc.may be used safely in combination. The polymerization initiators includeperoxides such as benzoyl peroxide and di-tert-butyl peroxide andazonitriles such as azobisisobutyronitrile.

The monomers containing at least one ethylenic unsaturated bond to beused in the invention include, for example, (meth)acrylic acid, methylinclude, for example, (meth)acrylic acid, methyl (meth)acrylate, ethyl(meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate,cyclohexyl (meth)acrylate, lauryl (meth)acrylate, glycidyl(meth)acrylate, styrene, vinyl acetate and (meth)acrylonitrile, andcompounds such as macromonomer having polymerizable (meth)acryloyl groupat the end of polystyrene and poly(meth)acrylate can also be used.

The monomers containing at least one ethylenic unsaturated bond and atleast one hydroxyl group to be used in the invention include, forexample, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylateand 2-hydroxybutyl (meth)acrylate, and (poly)caprolactone-modified(meth)acrylates esterified said hydroxyl group-containing (meth)acrylatewith caprolactones (e.g. trade name Praccel FA, Praccel FM series, etc.from Daicel chemical Industries) can also be used. Moreover, estersobtainable by reacting α,β-unsaturated carboxylic acid or its anhydridewith diols and 1,4-butene glycol, allyl alcohol, etc. can be used, ifthey are monomers or compounds which have an ethylenic unsaturated bondand a hydroxyl group. The amount of hydroxyl group introduced by saidmonomer preferably is 0.1 to 5 wt. % in the graft copolymerized resin.If less than 0.1 wt. %, the reaction liquor becomes milky turbid andseparates into two layers, resulting in a non-uniform and transparentsolution, despite graft copolymerization. If over 5 wt. %, then there isa possibility of gelation during graft copolymerization and adherence toa polyolefin also becomes poor.

The content of the mixture of carboxyl group-containing chlorinatedpolyolefin resin and oxidation treatment-provided chlorinated polyolefinresin in the graft copolymerized resin preferably is 5 to 90 wt. %. Ifless than 5 wt. %, the adherence to polyolefin is poor, and, if over 90wt. %, then the balance of physical properties of coated film isaggravated.

With the graft copolymerized resin of the invention, the physicalproperties such as gasoline resistance, weather resistance and moistureresistance, that are needed for paint and adhesive, can be enhanced byformulating an isocyanate compound or an alkyl-etherified amino resin asa curing agent. Suitable isocyanate compounds include aromatic,aliphatic and alicyclic organic diisocyanates, for example,tolylenediisocyanate, xylenediisocyanate, 1,5-naphthalenediisocyanate,1,4-tetramethylenediisocyanate, 1,6-hexamethylenediisocyanate,2,2,4-trimethylhexamethylenediisocyanate, isophoronediisocyanate,4,4-dichclohexylmethanediisocyanate and 1,4-cyclohexyldiisocyanate.Moreover, these organic diisocyanates may be modified to isocyanatederivatives such as the biuret form, the isocyanurate form and thetrimethylolpropane adduct form for use.

Furthermore, isocyanate compounds blocked with a blocking agent can alsobe used. The blocking agents include, for example, oximes such as methylethyl ketoxime, cyclohexanone oxime, formaldoxime and acetaldoxime,phenols such as phenol and cresol, alcohols such as methanol, benzylalcohol and ethylene glycol monomethyl ether, active methylene compoundssuch as methyl acetoacetate or acetic amide and, besides, imides,amines, imidazoles, ureas, carbamates, imines, mercaptans, sulfites andlactams.

Also, urethane resins having free isocyanate groups obtainable byreacting high-molecular polyols such as polyether polyol and polyesterpolyol with said organic diisocyanates, and others can be used, if theyare compounds having two or more isocyanate groups per molecule.

For the purpose of promoting the reactivity and deblocking reactivitybetween the graft copolymerized resin of the invention and theisocyanate compound being a curing agent, a reaction catalyst can beused. As the reaction catalysts, for example, dibutyl tin dilaurate,dibutyl tin fatty acid salt, dibutyl tin diacetate,tetra-n-butyl-1,3-diacetoxy-distannoxane, 3-dilauryloxydistannoxane,di-n-butyl tin oxide, mono-n-butyl tin oxide, stannous octylate and zincoctenate are exemplified.

The alkyl-etherified amino resins to be used as a curing agent in theinvention are obtained by reacting an amino compound such as urea,melamine or benzoguanamine with formaldehyde for methylolation and thenetherification with a lower alcohol such as methanol or butanol, and,for example, n-butyl-etherified urea resin, isobutyl-etherified urearesin, methyl-etherified melamine resin and n-butyl-etherifiedbenzoguanamine resin belong thereto. Moreover, for promoting thereaction between the graft copolymerized resin and the alkyl-etherifiedamino resin, acidic catalyst can be used. For example, there are alcoholsolution of hydrochloric acid, salt of strong acid like ammoniumchloride, phosphoric ester like monobutyl phosphate and organicsulfonate like p-toluenesulfonic acid.

The coating composition of the invention may be used by coating as itis, but pigment, solvent and other additives, for example, ultravioletabsorber, antioxidant and pigment sedimentation-preventing agent can beadded and kneaded and dispersed for use as a paint. Further, it can alsobe used as a primer for adhering or painting polypropylenix resin andvarious plastics.

Moreover, while said coating composition exhibits balanced physicalproperties by itself, but, if need be, alkyd resin, acrylic resin,polyacrylic polyol, polyester resin, polyester polyol, polyether resin,polyether polyol, polyurethane resin, chlorinated polyolefin, etc. mayfurther be added safely for use.

The features of the invention lie in that the mixed resins of carboxylgroup-containing chlorinated polyolefin resin and oxidationtreatment-provided chlorinated polyolefin resin have graft copolymerizedthere to a monomer containing an ethylenic unsaturated bond and amonomer containing an ethylenic unsaturated bond and a hydroxyl group,thereby improving the reactivity between chlorinated polyolefin havingsubstantially poor reactivity and said monomers to obtain a uniform andtransparent reaction liquor, and, at the same time, obtaining a coatingcomposition which exhibits good adherence also to polyolefins that towhich it has been difficult traditionally for such resin compositions toadhere.

Here, the polymers of the monomers are components which introducehydroxyl groups. They offer a crosslinking reaction with an isocyanatecompound or an alkyl-etherified amino resin, as well as indispensablecomponents to form the skeleton of graft copolymerized resin. Moreover,it is believed that the carboxyl group-containing chlorinated polyolefinresin also forms the skeleton of a graft copolymerized resin, but it isa component mainly to afford the adherence to polyolefin, and theoxidation treatment-provided chlorinated polyolefin resin works as acompatibilizer to improve the compatibility between the polymers of saidmonomers and the carboxyl group-containing chlorinated polyolefin resin.

Namely, it is considered that, by reacting said monomers, carboxylgroup-containing chlorinated polyolefin resin and oxidationtreatment-provided chlorinated polyolefin resin, the carboxyl group ofcarboxyl group-containing chlorinated polyolefin resin and the monomercontaining hydroxyl group give rise to the esterifying reaction and thegraft copolymerization progresses making this place as a reaction site.On the other hand, the oxidation treatment-provided chlorinatedpolyolefin resin has functional groups introduced there into bysubjecting the polyolefin to an oxidation treatment with air, oxygen,ozone, etc. during chlorination of the polyolefin. Although thesefunctional groups are not clear, the formation of carbonyl group,carboxyl group, acid chloride group, peroxide group, peroxide chloridegroup, etc. is conceivable. Moreover, the functional groups areconsidered to be formed at the time of a scission reaction of thepolyolefin, hence these functional groups are assumed to be introducedto the end of chlorinated polyolefin molecules. This functional groupand the monomer containing hydroxyl group are assumed to similarly giverise to the esterifying reaction to progress the graft copolymerization,making this place as a reaction site, but, it is considered that,different from the reaction product aforementioned between carboxylgroup-containing chlorinated polyolefin resin and monomer containinghydroxyl group, the reaction product does not become a networkhigh-molecule but becomes linear high-molecule with good solubility,because of the functional group existing at the end of molecule.

From the considerations as above, it is considered that, by reactingsaid monomers, carboxyl group-containing chlorinated polyolefin resinand oxidation treatment-provided chlorinated polyolefin resin, polymersof three components, i.e. polymers of monomers, graft copolymers ofcarboxyl group-containing chlorinated polyolefin resin with monomers,graft copolymers of oxidation treatment-provided chlorinated polyolefinresin with monomers, etc. are formed in the mixed state, and,particularly, the graft copolymers of oxidation treatment-providedchlorinated polyolefin resin with monomers being linear high-moleculeswith good solubility become compatibilizers between other polymers ofmonomers and graft copolymers of carboxyl group-containing chlorinatedpolyolefin resin with monomers, making it possible to obtainexceptionally uniform, transparent and balanced graft copolymers.

BEST EMBODIMENT FOR PUTTING THE INVENTION INTO PRACTICE

In following, the invention will be illustrated in more detail based onthe examples.

(TRIAL EXAMPLE 1)

In a three-necked flask equipped with stirrer, dropping funnel andcooling pipe for refluxing monomer were placed 5 kg of isotacticpolypropylene with a number average molecular weight of about 15,000,which was melted completely in an oil bath kept constantly at 180° C.After passing nitrogen inside the flask for about 10 minutes, 350 g ofmaleic anhydride were added over 5 minutes while stirring and then 35 gof di-tert-butyl peroxide dissolved in 50 ml of heptane were added overabout 30 minutes through a constant feed pump. At this time, the systemwas kept at 180° C. After continuing the reaction further for about 1hour, the unreacted maleic anhydride was removed over about 30 minuteswhile reducing the pressure inside the flask with an aspirator. Next, 5kg of this product were added to a glass-lined reaction vessel and 80liters of chloroform were added, which was dissolved completely at 110°C. under a pressure of 2.5 kg/cm². Then, while irradiating the contentswith ultraviolet rays, chlorine gas was passed into the flask to conductthe chlorination reaction. After completion of the reaction, solventchloroform was distilled off with an evaporator and substituted withtoluene to obtain a toluene solution with 30% solids. The chlorinecontent of this carboxyl group-containing chlorinated polypropylene(hereinafter referred to as MCPP) was 25 wt. % (based on solids) and thecontent of maleic anhydride was 4.2 wt. % (based on solids).

(TRIAL EXAMPLE 2)

Into 80 liters of carbon tetrachloride were homogeneously dissolved 5 kgof isotactic polypropylene with a number average molecular weight of5,000 under pressure, and, while irradiating the flask with ultravioletrays, chlorine gas was passed therein at a temperature of 100° to 110°C. to conduct the chlorination. When the chlorine content reached about20 wt. %, the chlorine gas was switched to a mixed gas of chlorine/airwith volume ratio of about 10/90, and the chlorination was conductedgradually while conducting an oxidation treatment. Tracking thefunctional group index aforementioned with infrared spectrophotometer onthe way of oxidation treatment, a sample with functional group index of15.5 and chlorine content of 30.2 wt. % was drawn out, carbontetrachloride was distilled and substituted with toluene to obtain anoxidation treatment-provided chlorinated polypropylene (hereinafterreferred to as OCPP) having a nonvolatile matter of 50 wt. %.

(TRIAL EXAMPLE 3)

Under similar conditions to Trial Example 2, 5 kg of isotacticpolypropylene with a number average molecular weight of 15,000 waschlorinated, and, when the chlorine content reached about 20 wt. %, amixed gas of chlorine/oxygen in a volume ratio of about 25/75 was passedtherein to conduct both the oxidation treatment and chlorination.According to the method of Trial example 2 thereafter, an oxidationtreatment-provided OCPP with functional group index of 16.5, a chlorinecontent of 31.8 wt. % and a nonvolatile matter of 50 wt. % was obtained.

(EXAMPLE 1)

Into a flask equipped with stirrer, thermometer and cooling pipe forrefluxing monomer were added 375 g of MCPP (nonvolatile matter 20 wt. %)and 175 g of toluene, and the temperature was raised to 85° C. Next,after adding 5 g of benzoyl peroxide and stirred for 30 minutes, 137 gof methyl methacrylate, 205 g of lauryl methacrylate and 58 g of2-hydroxyethyl acrylate were added over about 3 hours and the graftcopolymerization reaction was conducted further for about 7 hours toobtain a uniform and transparent reaction liquor (nonvolatile matter 50wt. %). Following this, 80 g of reaction product thus obtained and 26 gof titanium dioxide were kneaded for 2 hours in a sand mill and then 7.8g of isocyanate curing agent N35600 (hexamethylenediisocyanate type,isocyanurate form from Bayer Co.,) were added. After the viscosity wasadjusted with xylene so as to become 13 to 15 seconds/20° C. through No.4 Ford Cup, the material was spray painted onto a polypropylene plateTX-933A (from Mitsubishi Petrochemical Co., Ltd.). After drying for 15minutes at room temperature, the material was forcibly dried for 30minutes at 80° C. and allowed to stand for a week in room. The coatedfilm was tested. Results are shown in Table 1.

(EXAMPLE 2)

In a sand mill, 80 g of uniform and transparent reaction liquor(nonvolatile matter 50 wt. %) obtained in Example 1 and 26 of titaniumdioxide were kneaded for 2 hours, and then 17 g of alkyl-etherifiedamino resin curing agent Melane 11 (butyl-etherified urea resin,nonvolatile matter 60%, from Hitachi Chemical Co., Ltd.) and 20 g ofsolution of p-toluenesulfonic acid/36% hydrochloricacid/isopropanol=10/10/80 (ratio by weight) were added. After theviscosity was adjusted with xylene so as to become 13 to 15 seconds/20°C. through No. 4 Ford Cup, the material was spray painted onto apolypropylene plate TX-933A (from Mitsubishi Petrochemical Co., Ltd.).After drying for 15 minutes at room temperature, this material wasforcibly dried for 30 minutes at 120° C. and allowed to stand for a weekin room. Then the coated film was tested. Results are shown in Table 1.

(EXAMPLE 3)

Into a flask equipped with stirrer, thermometer and cooling pipe forrefluxing monomer were thrown-in 250 of MCPP (nonvolatile matter 20 wt.%) obtained in Trial example 1, 100 g of OCPP (nonvolatile matter 50 wt.%) and 250 g of toluene, and the temperature was raised to 85° C. Next,after adding 5 g of benzoyl peroxide and stirring for 30 minutes, with aformulating proportion of 171 g of methyl methacrylate, 171 g ofcyclohexyl methacrylate and 58 g of 2-hydroxyethyl acrylate, thereaction was conducted according to the method of Example 1 to obtain auniform and transparent reaction liquor (nonvolatile matter 50 wt. %).Following this, with a formulating proportion of 80 g of reactionproduct thus obtained, 26 g of titanium dioxide and 14.6 g of isocyanatecuring agent Desmodule Z4370 (isophoronediisocyanate type, isocyanurateform, from Bayer Co.), the paint adjustment and test of coated film wereperformed by the similar method to Example 1. Results are shown in Table1.

(EXAMPLE 4)

With a formulating proportion of 80 g of uniform and transparentreaction liquor (nonvolatile matter 50 wt. %) obtained in Example 1, 26g of titanium dioxide, 16.3 g of isocyanate curing agent SBU-Isocyanate0886 (block type polyisocyanate from Bayer Co.) and 0.5 g of catalystdibutyl tin dilaurate, the paint adjustment and test of coated film wereperformed by the similar method to Example 2. Results are shown in Table1.

(COMPARATIVE EXAMPLE 1)

Into a flask equipped with stirrer, thermometer and cooling pipe forrefluxing monomer were adding 200 g of OCPP (nonvolatile matter 50 wt.%) obtained in Trial example 2 and 400 g of toluene, and the temperaturewas raised to 85° C. Next, after adding 5 g of benzoyl peroxide andstirring for 30 minutes, with a formulating proportion of 205 g ofmethyl methacrylate, 137 g of lauryl methacrylate and 58 g of2-hydroxyethyl acrylate, the reaction was conducted according to themethod in Example 1 to obtain a uniform and transparent reaction liquor(nonvolatile matter 50 wt. %). Further, with the similar formulatingcomposition and recipe to Example 1, the paint adjustment and test ofcoated film were performed. Results are shown in Table 1.

(COMPARATIVE EXAMPLE 2)

Into a flask equipped with stirrer, thermometer and cooling pipe forrefluxing monomer were thrown-in 500 g of MCPP (nonvolatile matter 20wt. % obtained in Trial example 1 and 100 g of toluene, and thetemperature was raised to 85° C. Next, after thrown-in 5 g of benzoylperoxide and stirred for 30 minutes, with a formulating proportion of205 g of methyl methacrylate, 137 g of lauryl methacrylate and 58 g of2-hydroxyethyl acrylate, the reaction liquor (nonvolatile matter 50 wt.%) obtained showed milky turbidity and separated into two layers whenallowing to stand stationarily for a long period. Using this reactionliquor, with the similar formulating composition and recipe to Example1, the paint adjustment and test of coated film were performed. Resultsare shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                                  Comparative                                                                         Comparative                                         Example                                                                            Example                                                                            Example                                                                            Example                                                                            example                                                                             example                                             1    2    3    3    1     2                                         __________________________________________________________________________    Adherence ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                   ◯                                                                       ⊚                          Accelerated weather                                                           resistance                                                                    Gloss %                                                                       0 hour    91   92   92   90   89    71                                        200 hour  90   89   92   90   78    68                                        500 hour  88   87   91   88   70    63                                        1000 hour 86   85   88   87   65    53                                        Bright-                                                                       ness %                                                                        0 hour    86   86   87   86   85    63                                        200 hour  86   86   87   85   84    60                                        500 hour  85   85   85   84   84    56                                        1000 hour 84   84   85   84   83    52                                        Pencil hardness                                                                         HB   H    H    H    HB    HB                                        Gasoline resistance                                                                     ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                   X     ◯                             Moisture resistnce                                                                      ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                   X     Δ                                   Warm water resistance                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                   Δ                                                                             Δ                                   State of reaction                                                                       ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                   ⊚                                                                    XX                                        liquor                                                                        __________________________________________________________________________     Judgement criterion in table:                                                 ⊚: Good, ◯: Almost good, Δ: Slightly         poor, X: Poor, XX: Very poor                                             

Testing method of coated film

Adherence

On the surface of coated film, 100 cross-cuts reaching base were made atintervals of 1 mm. Cellophane adhesive tape was adhered closely thereonand peeled off in the direction of 180° C. to judge by the extent ofremaining coated film.

Accelerated weather resistance

A carbon arc type sunshine weathermeter was employed. The gloss wasmeasured by 60° C. mirror reflection and the brightness with Hunter.

Moisture resistance

Allowing to stand for 240 hours in an atmosphere of 50° C. and relativehumidity of 98%, the state of coated film and the adherence wereexamined.

Warm water resistance

The painted plate was dipped into warm water of 40° C. for 120 hours or240 hours and the state of coated film and the adherence were examined.

Gasoline resistance

A scratch (X mark) reaching base was engraved on the surface of coatedfilm and the painted plate was dipped into gasoline for 1 hour toexamine the state of coated film.

Possibility of Utilization in the Industry (From the Results of Table 1)

It can be seen that the reaction liquors graft coplymerized the mixtureof carboxyl group-containing chlorinated polypropylene and oxidationtreatment-provided chlorinated polypropylene with acrylic monomers areuniform and transparent, and further the coated films formulated withpolyisocyanate or alkyl-etherified amino resin as a curing agent givevery balanced coated films without injuring the adherence, appearance,gasoline resistance, weather resistance, moisture resistance, warm waterresistance, etc. On the other hand, in Comparative example 1 whereinoxidation treatment-provided chlorinated polypropylene was graftcopolymerized with acrylic monomers, the reaction liquor obtainedbecomes uniform and transparent, but the physical properties of coatedfilm are poor. Also, in Comparative example 2 wherein carboxylgroup-containing chlorinated polypropylene was graft copolymerized withacrylic monomers, the reaction liquor obtained gives rise to milkyturbidity and two-layer separation and the physical properties of coatedfilm are insufficient. From the results above, it is seen that theinventive coating compositions are very excellent.

We claim:
 1. A coating resin composition, comprising:(A) a graftcopolymerized resin prepared by graft polymerizing a monomer containingan ethylenic unsaturated bond and a monomer containing an ethylenicunsaturated bond and a hydroxyl group, onto a mixed resin of (i) acarboxyl group containing chlorinated polyolefin resin containing from 1to 10 wt. % of α,β-unsaturated carboxylic acid and/or anhydride andhaving a chlorine content of 5 to 50 wt. %, the resin (i) being preparedby a graft polymerizing α,β-unsaturated carboxylic acid and/or anhydrideonto a polyolefin followed by chlorination, and (ii) an oxidizedchlorinated polyolefin resin containing from 5 to 50 wt. % chlorine andhaving a functional group index of at least 1, wherein said index is 100times the ratio of absorbance at 1730 cm⁻¹ to absorbance at 2970 cm⁻¹prepared by oxidizing and chlorinating a polyolefin, wherein theoxidizing agent for the oxidation is at least one member selected fromthe group consisting of air, oxygen and ozone, the weight percent ratioof resin (i) to resin (ii) ranging from 5:95 to 95:5 and wherein themixed resins (i) and (ii) constitute from 5 to 90 wt. % of thecomponents of the graft polymerized resin of the composition; and (B) anisocyanate or alkyl-etherified amino resin as a curing agent.
 2. Thecoating resin composition of claim 1, wherein the polyolefin resin ofsaid chlorinated polyolefin resin is crystalline polypropylene,amorphous polypropylene, polybutene-1, polypentene-1, 4-methylpentene-1,low density or high-density polyethylene, ethylene-propylene copolymer,ethylene-propylene-diene copolymer, natural rubber or polyisoprene. 3.The coating resin composition of claim 1, wherein the α,β-unsaturatedcarboxylic acid and/or anhydride component of said carboxylgroup-containing chlorinated polyolefin resin is acrylic acid,methacrylic acid, maleic acid, maleic anhydride, citraconic acid,citraconic anhydride, fumaric acid, mesaconic acid, itaconic acid,itaconic anhydride, aconitic acid or aconitic anhydride.
 4. A method ofproducing a coating resin composition, comprising:(a) preparing a mixedresin of (i) a carboxylic group-containing chlorinated polyolefin resincontaining from 1 to 10% by weight of α,β-unsaturated carboxylic acidand/or anhydride and having a chlorine content of 5 to 50 wt. % andprepared by a graft copolymerizing an α,β-unsaturated carboxylic acidand/or anhydride onto a polyolefin followed by chlorination and (ii) achlorinated polyolefin resin containing from 5 to 50 wt. % chlorine andhaving a functional group index of at least 1 wherein said index is 100times the ratio of absorbance at 1730 cm⁻¹ to absorbance at 2970 cm⁻¹prepared by oxidizing and chlorinating a polyolefin, wherein theoxidizing agent for the oxidation is at least one member selected fromthe group consisting of air, oxygen and ozone, the weight percent ratioof resin (i) to (ii) ranging from 5:95 to 95:5; graft-copolymerizing amonomer containing an ethylenic unsaturated bond and a monomercontaining an ethylenic unsaturated bond and a hydroxyl group, such thatthe hydroxyl group content of the graft copolymerized resin formed upongraft copolymerization ranges from 0.1 to 5 wt. %, onto said mixed resinin the presence of a polymerization initiator, thereby preparing a graftcopolymerized resin; and combining an isocyanate compound or analkyl-etherified amino resin as a curing agent with the graftcopolymerized resin material, the mixed resins (i) and (ii) constitutingfrom 5 to 90 wt. % of the components of the graft polymerized resin ofthe composition.
 5. The method of claim 4, wherein the polyolefin resinof said chlorinated polyolefin resin is crystalline polypropylene,amorphous polypropylene, polybutene-1, polypentene-1, 4-methylpentene-1,low density or high-density polyethylene, ethylene-propylene copolymer,ethylene-propylene-diene copolymer, natural rubber or polyisoprene. 6.The method of claim 4, wherein the α, β-unsaturated carboxylic acidand/or anhydride component of said carboxyl group-containing chlorinatedpolyolefin resin is acrylic acid, methacrylic acid, maleic acid, maleicanhydride, citraconic acid, citraconic anhydride, fumaric acid,mesaconic acid, itaconic acid, itaconic anhydride, aconitic acid oraconitic anhydride.
 7. The coating resin composition of claim 1, whereinsaid carboxyl group-containing chlorinated polyolefin resin is acarboxyl group-containing chlorinated polypropylene;the oxidationtreated chlorinated polyolefin resin is an oxidation treated chlorinatedpolypropylene; said monomer containing an ethylenic unsaturated bond ismethylmethacrylate; said monomer containing an ethylenic unsaturatedbond and a hydroxyl group is 2-hydroxyethyl acrylate; and said curingagent is the isocyanurate form of hexamethylene diisocyanate.